1. Field of the Invention
The present invention generally relates to a fuel cell system and a control method for raising the temperature of a fuel cell used in the fuel cell system.
2. Background Information
A fuel cell system is an electric power generation system in which hydrogen (serving as fuel) and air (serving as oxidizer) are supplied to a fuel cell to allow electrochemical reaction to take place in the fuel cell to generate electric power. One example of this type of fuel cell system is disclosed in Japanese Laid-Open Patent Application No. 2005-166439. The fuel cell system disclosed in Japanese Laid-Open Patent Application No. 2005-166439 uses a solid electrolyte fuel cell in which an anode is provided on one side of a solid electrolyte, while a cathode is provided on the other side. Air is supplied as oxidizing gas to the cathode while fuel gas is supplied to the anode. Power is generated by reacting the fuel gas with the air. The fuel cell system is configured having a startup combustor for reforming or partially combusting fuel gas introduced from the exterior during startup and supplying the resulting gas as a reducing gas to the anode. An exhaust gas combustor is provided for burning the anode off-gas discharged from the anode side, while a heat exchanger is provided for heating air with the heat produced from the exhaust gas combustor.